﻿using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.SessionState;
using System.Drawing;
using System.ComponentModel ;
public partial class System_CheckCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

        this.CreateCheckCodeImage(GenerateCheckCode());
    }



		private string GenerateCheckCode()
		{
			int number;
			char code;
			string checkCode = String.Empty;

			System.Random random = new Random();

			for(int i=0; i<5; i++)
			{
				number = random.Next();

				if(number % 2 == 0)
					code = (char)('0' + (char)(number % 10));
				else
					code = (char)('A' + (char)(number % 26));

				checkCode += code.ToString();
			}
            //checkCode = "888888";
			Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));

			return checkCode;
            
		}

		private void CreateCheckCodeImage(string checkCode)
		{
			if(checkCode == null || checkCode.Trim() == String.Empty)
				return;

			System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 18.2)), 25);
			Graphics g = Graphics.FromImage(image);

			try
			{
				//生成随机生成器
				Random random = new Random();

				//清空图片背景色
				g.Clear(Color.White);

				//画图片的背景噪音线
				for(int i=0; i<25; i++)
				{
					int x1 = random.Next(image.Width);
					int x2 = random.Next(image.Width);
					int y1 = random.Next(image.Height);
					int y2 = random.Next(image.Height);

					g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
				}

				Font font = new System.Drawing.Font("Arial", 18, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
				System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
				g.DrawString(checkCode, font, brush, 2, 2);

				//画图片的前景噪音点
				for(int i=0; i<100; i++)
				{
					int x = random.Next(image.Width);
					int y = random.Next(image.Height);

					image.SetPixel(x, y, Color.FromArgb(random.Next()));
				}

				//画图片的边框线
				g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

				System.IO.MemoryStream ms = new System.IO.MemoryStream();
				image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
				Response.ClearContent();
				Response.ContentType = "image/Gif";
				Response.BinaryWrite(ms.ToArray());
			}
			finally
			{
				g.Dispose();
				image.Dispose();
			}
		}
}
